Circuit breaker



April 17, 1934. H, DQRFMAN 1,955,327

CIRCUIT BREAKER Original Filed Oct. 20. 1930 2 Sheets-Sheet 1 I Y w INVENTOR /7/'//9/ fi Dar/x7144 T RNEY Patented Apr. 17, 1934 UNITED STATES -ggssaazv cnuim rv BREAKER ""Hlller D. Dori'man}'-Mansfleld,sohiofassignor to Westinghouse Electric}; Manufacturing Company, a corporatio Application October 20;

Pennsylvania "1930, Serial No. 489,732

Renewed September 16, 1933 6 Claims.

My invention relates to circuit breakers and particularly to circuit breakers for controlling lighting and motor circuits and which may be mounted in sheet-metal enclosures.

An object of my invention is to provide a multipole circuit breaker wherein current-responsive trip mechanism is associated with at least three of the poles of the circuit, and wherein the trip mechanism releasably retains a single latch element of the circuit breaker in closed position, thereby rendering the circuit breaker responsive to current conditions in either of the three poles of the circuit.

A further object of my invention is to provide a simple current-responsive tripping element that may be applied to multi-pole circuit breakers of standard construction, and which may be .detachably mounted upon the circuit breaker base, in order to permit of interchange of current-responsive elements having different operating characteristics.

The further object of my invention is to provide a circuit-breaker for a multi-pole circuit wherein a single latch arm serves to releasably retain all of the contacts of the multi-pole circuit breaker from being tripped, and wherein a separate latch-operating member is associated with each pole of the circuit breaker for individually operating the retaining member, and wherein a separate independently operable current-responsive member serves to releasably restrain each oi the latch-operating members, whereby the circuit breaker may be tripped to open position in response to current conditions in the circuit with which any one of the currentresponsive members is associated.

These and other objects that will be made apparent throughout the further description of my invention are obtained by the apparatus hereinafter described. and illustrated in the accompanying drawings wherein,

Figure 1 is a top plan view f a multi-pole circuit breaker embodying features of my invention;

Fig. 2 is a side elevational view, partially in section, of the circuit breaker shown in Fig. 1, the section being taken on the broken line IL-II of Fig. 1;

Fig. 3 is an end elevational view, partially in section, of the circuit breaker shown in Fig. 2, taken on line III-III thereof; 7

Fig. 4 is a top plan view of a latch plate constituting a part of the structure shown in Figs. 1 and 2;

Fig. 5 is a side elevational view of a trip member'shown in Figs. 1 and 2.

Referring to the drawings, the circuit breaker comprises an insulating base 7 upon which is mounted a sheet-metal-frame structure 8 which serves to support the circuit-breaker unit of a construction similar to that minutely described in the copendingapplication, Serial No. 356,646, filed by O. S. Jennings, April 20, 1929 now Patent 1,794,901, issued March 3, 1931 and assigned to the assignee of this application.

Briefly the circuit breaker unit comprises the frame 8 upon which a cradle 9 is pivoted for ro tative movement about a pivot pin 11. An operating arm 12, having a handle 13, is pivoted for rotative movement about the pivotpin 14, and a pair of tension springs (one of which is shown) are attached, at their outer ends, to the arm 12 and, at their inner ends, to the knee pivot 16 of a pair of toggle links 1'1 and 18 which serve to operate a pivoted switch arm 19 that is mounted to oscillate about a pivot shaft 21 mounted on the frame 8 the link 1'7 being pivoted to the arm 19 by the pivot shaft 22, and the toggle-link 18 being pivotally connected to the cradle 9 at-the point 23 in the apex of a notch 24 of V-shape in the cradle 9.

I The contact arm 19 carries a flexible leaf spring 25, upon the free end of which is mounted a movable contact 26 that is adapted to engage a stationary contact 27.

The cradle 9 is releasably retained in the closed position shown in Fig. 2 by means of a latch arm 34 that will be hereinafter described. The circuit-breaker apparatus may be designated as of the tumbler type wherein an overcenter spring serves to move the contact to open and to closed positions. As shown in Fig. 2, the contact 26 is in open position and is moved to closed position, with a snap action, when the operating handle 13 has been moved clockwise a suflicient distance to move the outer ends of the springs 15 past a center line traversing the pivot shaft 16 and the point 23 referred to above. When this movement of the operating handle has been accomplished, the springs 15 will snap the lower pivot shaft 16 toward the right to straighten the toggle links for forcing the contact 26 into the closed Dosition.

When it is desired to move the switch toopen position manually, the operating handle 13 is moved to the left or in a counter-clockwise direction, and, when the springs 15 again pass over the above-mentioned center line, the toggle will be broken with a snap action to cause the contact 26 to be quickly separated from the contact 27.

In the event of an overload or a short-circuit condition, the latch arm 34 is released, in a manner to be hereinafter described, and the springs 15, which are in extended stressed condition when .able for a multi-pole circuit breaker.

However, it is to be understood that the present form of circuit breaker, as disclosed in Fig. 1 is of the three-pole type in which the operating mechanism above described is employed for operating three contact arms 19 that are connected, at their inner ends, by means of an insulating cross bar 29.

The current-respo isive tripping or releasing device comprises a metal frame 31 of U shape that is mounted upon the base 7 and supports a resetting shaft 32, that is turned for rotation in the side-plates 33 of the frame and held against longitudinal movement by cotter pins 35.

The cradle 9 of the circuit breaker is provided with a latch arm 34 that is releasably retained in the operative position shown in Fig. 2, wherein the contact arm 19 of the circuit breaker may be manually moved to open and to closed position, by a latch 35 that is rotatably mounted upon the shaft 32 as indicated in Figs. 1 and 3, the end of the latch arm 34 being adapted to extend into a notch 36 in the latch 35 to engage the upper end of the notch at the point 37. The latch 35 is releasably retained in its latch-retaining position by means of a latch plate 38, that is pivotally mounted upon the pivot pins 39 secured to the side plates 33 of the frame 31. v

The latch plate 38 is provided with a rectan gular opening 41 to receive the inner extremity 42 of the latch 35 and retain it in latch-retaining position against the bias of the latch arm 34, which normally tends to rotatively move the latch 35 in a counter-clockwise direction. The latch plate 38 is biased in a counterclockwise direc tion by means of three helical springs 43, and the upward movement of the latch 38 is limited by stop members 44 that are struck inwardly from the side plates 33 of the frame, as indicated in .Figs. 1 and 2.

The latch plate 38 is provided with three posts or buttons 45 adapted to be engaged by a trip finger 46 extending from each of three trip members or earns 47 that are rotatably mounted upon the resetting shaft 32, directly opposite each of the buttons 45, as indicated in Figs. 1 and 3. The trip cams 47 are normally biased in a counterclockwise direction by helical springs 48 that are secured, at one end, to a cross member 49 of the frame 31, and, at the other end, to nibs 51 on the cams .47.

Each of the cams -47 engages the resetting shaft 32 through a lost-motion connection comprising one of the pins 52 which project from the outer face of the shaft 32, and one of the pins 53 which extend laterally from the side of the cams themselves. The engagement of the pins 52 and53 does not take place until the cams 47 have been moved counter-clockwise a sufficient distance to depress the latch plate 38, by reason of the engagement of the fingers 46 with their respective buttons 45, sutficiently to disengage the latch 35 from engagement with the latch plate 38 which thus serves as a trip bar.

The trip cams 4'7 are releasably retained inactive, in the position shown in Fig. 2, by means of the independently operable current-responsive bimetal elements 54 which are provided, at their free ends, with insulated latch clips 55 adapted to be engaged by a shoulder 56 on the periphery of the cams 47. The bimetal elements 54 are of the. usual U-shape construction, and they are each connected in series with one pair of contacts of the multi-pole circuit breaker in such manner that they are responsive to the current passing through the circuit connected to that particular pair of contacts.

If an over-load or short circuit condition appears in any one of the circuits controlled by the contacts of the circuit breaker, the bimetal element 54, that is associated with that circuit, will be heated by the excess current, and the free end of the bimetal element will move outwardly a sulficient distance to cause the latch clip 55 to clear the shoulder 56 of its respective trip cam 47. The spring 48 will immediately cause counterclockwise rotation of the cam and release the latch 35 by depressing the latch plate or trip bar 38 in the manner described. The instant' the latch 35 is released and rotated counterclockwise, the latch arm 34 will be released to cause the circuit breaker contacts to move to the open circuit position with a-snap action. It will be seen, therefore, that the circuit breaker is tripped to open position whenever an overload or short-circuit condition occurs in any one of the poles of the circuit controlled by the circuit breaker.

After the circuit breaker has opened, it may be reclosed by so manipulating the handle of the circuit breaker as to cause counter-clockwise rotation of the cradle 9 and its latch arm 34. During the reclosing operation, the inner edge of the rounded latch arm 34 will first engage a resetting lever 57 that is attached to the shaft 32 at a point opposite the notch 36 in the latch 35 and thereby cause clockwise movement of the lever 57 and the shaft 32. The pins 52 on the shaft, at this time, engage the pins 53 on the trip cams 47 and cause clockwise rotation thereof, until the shoulder 56 on each of the cams clears the latch clip 55 on the bimetal elements 54. Then, assuming that the bimetal element 54 has sufiiciently cooled to permit it to move inwardly to its original position, the shoulders 56 of the latch cams 47 will engage-the latchclips 55 to retain them in the inactive position shown in Fig. 2.

This rotation of the shaft 32 permits the free return of the latch-plate 38 to its original position just as soon as the latch 35 has been moved to the latch-retaining position indicated in Fig. 2. The free end of the latch-plate 38 is bent inwardlyto provide a curved surface 58' over which the extremity 42 of the latch 35 passes when the latch 35 is moved in a clockwise direction. The extremity 42 depresses the latch 38 until the extremity registers with the notch 41 in the plate 38, at which time the latch-plate 38 will be moved upwardly (Fig. 2) by the springs 43 thereby releasably retaining the latch 35 in the latch-retained position shown in Fig. 2.

It is apparent from the foregoing, that the single reclosing movement of the cradle 9 causes resetting of the various latches and the trip cams and that all of the parts are returned to their original positions wherein they stand ready to cause the circiut breaker to be tripped to open position in response to any subsequent overload on shortcircuit condition occurring in the circuit controlled by any one of the poles of the circuit breaker. The latch-plate 38 is provided with openings 59 through which the bimetal elements 54 extend, and these openings 59 which are of such dimensions as to permit withdrawal of the latch-plate 38 and its associated frame 31 from the base or circuit-breaker structure without interference therewith. The trip mechanism may,

therefore, be removed from the base without interrfering with the bimetal elements 54 of the circuit breaker, and the bimetal elements are detachably mounted upon the base '7 and may be interchanged with other bimetal elements having different current-responsive characteristics in order to change the current rating of the circuit breaker.

While I have illustrated but one embodiment of my invention, it will be apparent to those skilled in the art that various changes, modifications, substitutions, additions and omissions may be made in the apparatus illustrated without departing from the spirit and scope of my invention as set forth in the appended claims.

I claim as my invention:

1. A trip device for a multi-pole circuit breaker including a latch arm movable when released to cause opening of the several poles of the circuit breaker a latch member for releasably engaging said latch arm and an independently movable latch release member upon the actuation of which said latch arm is disengaged from said latch member, a separate independently operable trip-member for each of two or more poles of the circuit breaker normally biased toward tripping position and any one of which, when released, causes movement of said latch release member to release the latch member, and a separate independently operable current-responsive member associated with each of said two or more poles of the circuit breaker for releasably retaining the trip members nonactive.

2. A trip device -for a multi-pole circuit breaker comprising a latch arm for releasably retaining the contacts of the several poles of the circuit breaker from being tripped, a latch for retaining said latch arm in contact retaining position, a separate independently operable trip-member for each of two or more poles of the circuit breaker normally biased toward tripping position and any one of which, when released, causes the release of said latch arm, a separate independently operable current-responsive trip member associated with each of said two or more poles of the citcult breaker for releasably retaining said trip members non-active, and means for returning the trip members to their inactive position before the latch arm is returned to its retaining position.

3. A trip device for a multi-pole circuit breaker comprising a latch member releasable for causing opening movement of the contacts of the several poles of the circuit breaker, a resetting shaft operable by the latch member, a separate independently operable trip member associated with each of two or more poles of the circuit breaker mounted thereon and having a lost-motion connection thereto and normally biased toward tripping position and each of which, when released, causes the release of the latch member, and a separate independently operable currentrcsponsive member associated with each of said two or more poles of the circuit breaker for releasably retaining the trip members non-active.

4. A trip device for a multi-pole circuit breaker comprising a latch member releasable for causing opening movement of the contacts of the several poles of the circuit breaker, a resetting shaft operable by the latch member, a second latch member rotatably mounted on the resetting shaft for releasably retaining the first latch member in operative position, a third latch member for releasably retaining thesecondlatchmemher in latch-retaining position, a separate independently operable trip member associated with each of two or more poles of the circuit breaker and mounted upon, and having a lost-motion connection to the resetting shaft and normally biased toward tripping position and each of which, when released, actuates the third latch member to releasing position, and a separate independently operable current-responsive member associated with each of said two or more poles of the circuit breaker and cooperating with its respective trip member for releasably retaining the latter in inactive position, the said resetting shaft, when actuated by the first latch member, acting to reset the said trlp members with respect to their respective current-responsive members.

5. A trip device for a multi-pole circuit breaker including means for retaining the contacts of all of the poles of the circuit breaker from being tripped to open position, said retaining means being releasable for allowing the opening of said contacts, a separate current-responsive device electrically connected with each of two or more poles of said circuit breaker, an independently operable trip member operable by each of said current responsive devices and being movable to tripping position in response to a predetermined current flow in said device, a trip bar extending across said trip members and movable by any one thereof to cause the release of said retaining means to open the contacts of all the poles of said circuit breaker, and means actuated by the circuit breaker for resetting all of said tripping members to non-tripping position before said contacts are closed after being tripped to open position.

6. In a multi-pole circuit breaker, an operating member for opening and closing the contacts of all the poles of said circuit breaker, means for opening said contacts irrespective of the position of said operating member and retaining means for holding said contacts from being tripped to open position, a separate movable current responsive element for each of two or more poles of the circuit breaker, a separate pivoted trip member biased to tripping position and held in nontripping position by each of said current responsive elements, a single trip bar movable by any one of said trip members to release said retaining means to open the contacts of all the poles, and means for resetting each of said trip members to non-tripping position before said contacts are closed after being tripped to open. position.

HILLER D. DORFMAN.

n add DISCLAIMER 1,955,327.-H'iller D. Dorgfman Mansfield, Ohio. CIRCUIT BREAKER. Patent dated April 17, 1934. Disciaimer filed March 20, 1941, by the assignee, Westinghouse Electric (2 Manufacturing Company. Hercb enters this disclaimer to claims 2, 5, and 6 of the patent.

[ flic'lal Gazette Apr-18, 1941.] 

